Antenna system



J. A. KUECKEN ANTENNA SYSTEM Filed April 21, 1967 Jun: 30, 1970 I N VEN TOR JOHN A. KUECKE/V ATT).

United States Patent US. Cl. 343--848 6 Claims ABSTRACT OF THE DISCLOSURE An antenna system having a vertical radiating element and a plurality of ground plane arms forming a ground plane. The conductive length of each of the arms is adjustable so as to steer or adjust the radiation pattern of the vertical radiating element to a desired shape.

The present invention relates to antenna systems which are adapted to have their radiating pattern varied.

Often a requirement is placed upon an antenna system that its radiation pattern be made adjustable to make it suitable for either short range or long range communications. Moreover, other usual requirements are that the antenna system be not only easily installed but also quickly tuned. Unfortunately, these requirements for most existing antenna systems are at cross purposes. That is to say, an antenna system may be easily installed but difficult to tune.

Accordingly, an object of the present invention is to provide an improved readily installable antenna system which has an adjustable radiating pattern and which is quickly installed and tuned.

Briefly described, an antenna system embodying the invention has a vertical radiator and a plurality of conductive ground plane arms. The conductive length of the ground plane arms are independently adjustable. Thus,

the radiation pattern of the vertical antenna may actually be contoured to a desired shape.

An important feature of the invention is the provision of improved means for adjusting or varying the conductive length of radial arms comprising the ground plane.

The invention itself, both as to its organization and method of operation, as well as additional objects and advantages thereof, will become more readily apparent from a reading of the following description in connection with the accompanying drawings in which:

FIG. 1 is a perspective view diagrammatically illustrating an antenna system in accordance with the invention showing a vertical whip antenna and a plurality of radial arms forming the ground plane for the vertical whip. Portions of the arms at A and B in FIG. 1 are exploded as shown in FIGS. 2 and 3, and in different operational positions, showing how to change the conductive length of a radial arm.

Referring more particularly to the drawing a representative antenna system 10 is shown which may operate in the high frequency band. A vertical monopole radiator 12 and a plurality of radial arm elements 16 which comprise a ground plane, comprise the antenna.

The arms 16 are spaced from the earth 14. The antenna 10 is fed via a coaxial feed line 17, which in turn is coupled to a transmitter, not shown. At the feeding junction between the coaxial cable 17 and the antenna system 10, the outer coaxial conductor engages the ground plane arms 16 whereas the inner conductor feeds the vertical monopole radiator 12.

Also included within the antenna system 10 are a plurality of guide wires 20 and a supporting structure 22 which secures the monopole 12. Both these members are formed of an insulating material so as not to significantly effect the radiating pattern of the monopole 12.

A whip (unsupported, except at its base) monopole may also be used.

Each arm 16 includes a plurality of light weight coupling devices 28 (see FIGS. 2 and 3) which are movable between conducting and non-conduncting positions to thereby change the conductive length of each of the arms 16. The free end of each arm 16 is fastened to the earth 14 by means of an anchor. Just before the anchor is a stake element 32 which functions to hold its associated arm in a spaced relation from the ground 14.

By reducing the conductive length of the arms 16, the radiation pattern of the antenna system 10 elevates. When the conductive length of the arms 16 is extended, the radiation pattern (viZ. the angle of the launch pattern) lowers.

By way of illustration of the utility of the above princlple but without limitation, when broadcasting over long distance, say for example 900 miles, the current practice has it that the monopole 12 should be dimensioned to be about /2)\ (A being the wave length of the operation frequency) and the ground plane should have at least about eight conductive arms 16. To reduce the broadcasting range without reducing the length of the whip 12, all that need be done is to reduce the conductive length of the arms 16, and to extend the broadcasting range the arms 16 should be extended.

For shorter range broadcasting, it has been found that when the whip 12 is below M4, an effective way to match the impedance of the antenna system 10 to the coaxial line 17 (viz. to tune the antenna) is to vary the conductive length of the arms 16.

Referring now to FIGS. 2 and 3, the light weight coupling devices 28 are comprised of a ring shaped conductive center core member 38 surrounded by insulating material such as laminated plastic 40. Each coupler 28 is formed with a hollow interior 44 in such a manner so that two opposite disposed portions 46 of the conductive core 38 are exposed and may be engaged by loops 52 formed in the radial arms 16 in the manner shown in FIG. 2, thereby providing a conductive path by way of the core 38 up to the next coupler 28. To terminate the conduction of a radial arm 16 at a coupler 28, all that need be done is to rotate the coupler 28 to its position shown in FIG. 3, whereby each of the loops will only engage the insulating material 40 surrounding the conductive core.

From the foregoing description it will be apparent that there has been provided an improved ground plane antenna system. Variations and modifications of the illustrated antenna system will undoubtedly become apparent to those skilled in the art. For example, the ground plane could be somewhat distorted to form an apex-down cone which would raise the position of the main lobe of the radiation pattern. Moreover, the guide wires 20 could be made of conductive material to change the radiation resistance of the antenna system. Accordingly, the fore going description should be taken as illustrative and not in any limiting sense.

What is claimed is:

1. An antenna system comprising:

(a) a vertical radiating element,

(b) a ground plane having a plurality of arms extending outwardly with respect to said vertical element, and said arms having conductive portions separated by couplers, said couplers having insulative and conductive parts, and

(c) means for varying the conductive length of said arms by alternatively presenting said insulative and conductive portions to adjacent arm portions separated thereby to adjust the radiation to adjust the radiation pattern of said antenna system.

2. The invention as set forth in claim 1 wherein said radiator is a monopole and said arms extend radially therefrom.

3. The invention as set forth in claim 1 wherein said ground plane is spaced from the earth.

4. The invention as set forth in claim 1 wherein a plurality of said couplers are interposed in each arm with, each said coupler having a first position in which said insulative portion thereof is presented and a second position in which said conductive portion is presented, each of said couplers being adapted to be moved between said positions to change the conductive length of its arm.

5. The invention as set forth in claim 4 and wherein each said coupler is comprised of a conductive core element surrounded by an insulating material but leaving two exposed portions which are engageable by said radial elements in said second position.

6. The invention as set forth in claim 5 wherein said couplers are rings having a square hole said exposed portions being disposed at opposite corners of said hole.

References Cited ELI LIEBERMAN, Primary Examiner S. CHATMON, 1a., Assistant Examiner U.S. Cl. X.R. 343829, 849 

